Matter, Energy and Matter, Energy and ChangeChange

Chemistry and MeasurementChemistry and Measurement

Sections 1.3 – 1.4Sections 1.3 – 1.4

ChemistryChemistry

Chemistry is the study of matter and the Chemistry is the study of matter and the changes it undergoes.changes it undergoes.

What is matter?What is matter? How is matter classified?How is matter classified? What physical and chemical properties What physical and chemical properties

does matter possess?does matter possess?

SolidSolid

States of Matter (Phases)States of Matter (Phases)

Physical PropertiesPhysical Properties

Physical Physical Properties:Properties: Characteristics that Characteristics that

can be observed can be observed without without changing changing the chemical the chemical composition of the composition of the substancesubstance

Physical PropertiesPhysical Properties

Examples of physical Examples of physical properties:properties:

• States of matter States of matter (Phases) (Phases) s = solid; s = solid;

l = liquid; g = gasl = liquid; g = gas• ColorColor• SizeSize• OdorOdor• Mass (grams = g)Mass (grams = g)• Density (mass/volume)Density (mass/volume)

• VolumeVolume• TextureTexture• Solubility (maximum Solubility (maximum

amount of solute that amount of solute that can be dissolved in a can be dissolved in a solvent)solvent)

• ViscosityViscosity• Boiling point (bp)Boiling point (bp)• Freezing point (fp)Freezing point (fp)• Melting point (mp)Melting point (mp)

Chemical PropertiesChemical Properties

Description of what happens when two Description of what happens when two substances react with one anothersubstances react with one anotherFor example: Was heat, light, sound, or some For example: Was heat, light, sound, or some

other form of energy generated? Did a reaction other form of energy generated? Did a reaction take place at all (if not, the materials are non-take place at all (if not, the materials are non-reactive - which is a chemical property)?  Were reactive - which is a chemical property)?  Were gases formed?  Was it endothermic or exothermic? gases formed?  Was it endothermic or exothermic?

Endothermic & Exothermic Endothermic & Exothermic ReactionsReactions

Endothermic reaction: chemical reactions Endothermic reaction: chemical reactions which absorb heat in order to proceedwhich absorb heat in order to proceed Barium hydroxide reacts with ammonium Barium hydroxide reacts with ammonium

nitratenitrate Demo: Demo:

http://www.youtube.com/watch?v=GmiZ0huvZhttp://www.youtube.com/watch?v=GmiZ0huvZzszs

Endothermic & Exothermic Endothermic & Exothermic ReactionsReactions

Exothermic reaction: chemical reactions Exothermic reaction: chemical reactions that release energy in the form of heat, that release energy in the form of heat, light or sound; produce heat and may be light or sound; produce heat and may be explosiveexplosive Potassium permanganate Potassium permanganate Demo: Demo:

http://www.youtube.com/watch?v=80Q3GgeeIhttp://www.youtube.com/watch?v=80Q3GgeeIVM&feature=relatedVM&feature=related

Physical and Chemical ChangesPhysical and Chemical Changes

Physical changePhysical change: change that does not : change that does not alter the chemical composition of a alter the chemical composition of a substancesubstance E.g. change in state, dissolves in water E.g. change in state, dissolves in water

(aqueous)(aqueous)

Physical ChangesPhysical Changes

Physical and Chemical ChangesPhysical and Chemical Changes

Chemical changeChemical change: change that results in a : change that results in a new substance with new properties and new substance with new properties and chemical composition; materials combine chemical composition; materials combine chemically with another material , and chemically with another material , and cannot be separated by any physical cannot be separated by any physical means. means. E.g. color change, formation of a precipitate, E.g. color change, formation of a precipitate,

evolution of a gas, burning, oxidation (rusting)evolution of a gas, burning, oxidation (rusting)

Chemical ChangesChemical Changes

http://www.youtube.com/watch?v=opY3FLrPTa4

Conservation of Mass, EnergyConservation of Mass, Energy

Law of Conservation of MassLaw of Conservation of Mass Total mass remains constant during a Total mass remains constant during a

chemical reactionchemical reaction Law of Conservation of Mass is why we Law of Conservation of Mass is why we

must balance equations (# of atoms in must balance equations (# of atoms in reactants must equal # of atoms in reactants must equal # of atoms in products)products)

Changes of mass (i.e. loss of heat) in Changes of mass (i.e. loss of heat) in chemical reactions are too small to detect chemical reactions are too small to detect

Mixtures and Pure SubstancesMixtures and Pure Substances

MIXTURES - MIXTURES - A mixture can be physically A mixture can be physically separated into pure compounds or separated into pure compounds or elements.  elements.   Just about everything that you can think of is Just about everything that you can think of is

probably a mixture. probably a mixture. Examples: concrete, salt waterExamples: concrete, salt water

Mixtures and Pure SubstancesMixtures and Pure Substances

  PURE COMPOUNDS - PURE COMPOUNDS - A pure compound A pure compound has a constant composition with fixed has a constant composition with fixed ratios of elements.ratios of elements. Example: distilled water contains water Example: distilled water contains water

molecules and molecules and onlyonly water molecules water molecules

Mixtures & Pure SubstancesMixtures & Pure Substances

Law of Definite Proportions: states that chemical Law of Definite Proportions: states that chemical compounds always contain the same ratio of compounds always contain the same ratio of elements by masselements by mass Water is always 1 g of hydrogen to 8 g of oxygenWater is always 1 g of hydrogen to 8 g of oxygen

Law of Multiple Proportions: when elements Law of Multiple Proportions: when elements combine, they do so in a ratio of small whole combine, they do so in a ratio of small whole numbersnumbers Carbon and oxygen react to form CO or COCarbon and oxygen react to form CO or CO22, not , not

COCO1.81.8